added frexp support to SkSL

This includes an optimizer fix for the situation:

int i;
float f = frexp(foo, i);

If we don't read the variable i, it is considered dead and eliminated -
which then causes an error when we try to write the expression
frexmp(foo, i).

Bug: skia:
Change-Id: Iac385e38e215455346fab62e1f4ec46fa65b3c21
Reviewed-on: https://skia-review.googlesource.com/116521
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/sksl/SkSLIRGenerator.h b/src/sksl/SkSLIRGenerator.h
index 327fe6fc7a..e8ff1d21c8 100644
--- a/src/sksl/SkSLIRGenerator.h
+++ b/src/sksl/SkSLIRGenerator.h
@@ -50,6 +50,7 @@
 #include "ir/SkSLType.h"
 #include "ir/SkSLTypeReference.h"
 #include "ir/SkSLVarDeclarations.h"
+#include "ir/SkSLVariableReference.h"
 
 namespace SkSL {
 
@@ -162,7 +163,7 @@ private:
 
     void fixRectSampling(std::vector<std::unique_ptr<Expression>>& arguments);
     void checkValid(const Expression& expr);
-    void markWrittenTo(const Expression& expr, bool readWrite);
+    void setRefKind(const Expression& expr, VariableReference::RefKind kind);
     void getConstantInt(const Expression& value, int64_t* out);
 
     Program::Kind fKind;